Using Doppler ultrasound to examine fetal circulation reduces perinatal death in high-risk pregnancies by 29%, an updated Cochrane Review found.

Action Points

Explain to interested patients that this review found that a Doppler ultrasound examination reduces perinatal death in high-risk pregnancies, although evidence is limited regarding the best approaches following an abnormal finding.

Using Doppler ultrasound to examine fetal circulation reduces perinatal death in high-risk pregnancies by 29%, an updated Cochrane Review found.

In a pooled analysis of 16 studies involving 10,225 babies, the perinatal death rate was 1.2% when Doppler ultrasound was used and 1.7% when it was not, according to Zarko Alfirevic, MD, of the University of Liverpool in England, and colleagues.

The number needed to treat was 203 (95% CI 103 to 4352).

In an interview, Alfirevic said that that high number and "absolutely huge" confidence interval reflects the lack of quality evidence.

"I think that, indeed, one can question whether this is a good value for money," he said, noting that there have not been any formal cost-effectiveness analyses.

But, because there are no obvious negative effects from the examination, he said, "I would expect that most patients would say Yes."

The review updated a previous one conducted in 1996, which came to similar conclusions about the use of Doppler ultrasound.

However, a false-positive finding could encourage inappropriate early delivery, which could result in increased problems associated with prematurity, Alfirevic and his colleagues wrote.

So they conducted a review to assess the risks and benefits of adding Doppler ultrasound to protocols for evaluating fetal well-being in women with high-risk pregnancies, including those with diabetes, hypertension, and heart problems or those with intrauterine growth restriction, pregnancies that have progressed beyond term, and those who've had a previous miscarriage or stillbirth.

The researchers looked at randomized and quasi-randomized controlled trials comparing the use of Doppler ultrasound with no ultrasound or with electronic fetal monitoring. In general, they said, the studies were not high quality.

In fact, the quality of the studies assessing Doppler ultrasound versus no ultrasound for the effect on perinatal death rates was "very low," the authors wrote, which is "of concern given the borderline significance of the pooled meta-analysis result."

There was insufficient evidence to assess the effect of the use of ultrasound on serious neonatal morbidity, the other primary outcome.

Although Alfirevic said he and his colleagues were concerned that the use of Doppler ultrasound might increase invasive obstetrical procedures, in 10 of the studies there were actually fewer inductions of labor (pooled RR 0.89, 95% CI 0.80 to 0.99) and fewer cesarean deliveries in 14 studies (pooled RR 0.90, 95% CI 0.84 to 0.97).

The use of Doppler ultrasound had no effect on rates of operative vaginal births or on the proportion of babies born with Apgar scores under 7 at five minutes.

According to Alfirevic, the overall low quality of the evidence did not allow for recommendations regarding patients who would most benefit from the addition of Doppler ultrasound or regarding the best approaches following an abnormal result.

"Doppler studies of the umbilical artery should be incorporated and should be a part of the protocols for fetal monitoring in high-risk pregnancies, particularly those who are at risk of placental insufficiency," he said.

"But we are not in a position at the moment to be more specific than that."

The review received internal support from the University of Liverpool and external support from the U.K. National Institute for Health Research (NIHR). One of Alfirevic's co-authors is supported by the NIHR NHS Cochrane Collaboration Program grant scheme award for NHS-prioritized centrally-managed, pregnancy and childbirth systematic reviews.